document.getElementById("verifyForm").addEventListener("submit", function (event) {
    // 获取用户名的值
    var username = document.getElementById("username").value;

    // 验证用户名是否为空
    if (username === "") {
        document.getElementById("usernameError").textContent = "用户名不能为空";
        event.preventDefault();
        return false;
    } else {
        document.getElementById("usernameError").textContent = "";
        return true;
    }
});